Julez,
I remember you from when I first joined SR. I only come here off and on now.
I can understand that voice that says you are relaxed and feel good so it is okay to drink. And I can see why it is tempting to drink, since part of the time it goes ok. I don't know if it is possible to be a situational alcoholic.
It helps that you've been sober and enjoyed it. I think that makes it so much easier to get sober again. (But it can still be hard.) I think it helps to already have that sense that sobriety feels good. It is often that sense of how good sobriety feels in my body that keeps me from drinking, although I get tempted and I have drank a few times in the past few years.
Take good care of yourself! Be gentle with yourself.